U.S. patent number 5,394,160 [Application Number 07/940,453] was granted by the patent office on 1995-02-28 for portable radio with coplanar ground and atenna conductive films formed on the inner surface of the case.
This patent grant is currently assigned to NEC Corporation. Invention is credited to Hiroyuki Iwasaki, Yukio Yokoyama.
United States Patent |
5,394,160 |
Iwasaki , et al. |
February 28, 1995 |
Portable radio with coplanar ground and atenna conductive films
formed on the inner surface of the case
Abstract
In a portable radio communication apparatus comprising an
insulating case having an inner surface and a printed board housed
in the insulating case, an antenna conductive film is coated on a
predetermined region of the inner surface of the insulating case. A
conductive ground film is coated on the remaining region of the
inner surface of the insulating case with a constant gap from the
outer periphery of the antenna. A first conductive member connects
the antenna film with the conductive ground film. A plurality of
second conductive members connect the conductive ground film with a
ground pattern of a radio communication circuit on the printed
board. A feeding member connects the antenna with an antenna
terminal pad of the radio communication circuit. The second
conductive members and feeding member are conductive rods.
Inventors: |
Iwasaki; Hiroyuki (Tokyo,
JP), Yokoyama; Yukio (Tokyo, JP) |
Assignee: |
NEC Corporation (Tokyo,
JP)
|
Family
ID: |
17247193 |
Appl.
No.: |
07/940,453 |
Filed: |
September 4, 1992 |
Foreign Application Priority Data
|
|
|
|
|
Sep 4, 1991 [JP] |
|
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3-253148 |
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Current U.S.
Class: |
343/702; 343/767;
343/841 |
Current CPC
Class: |
H01Q
1/243 (20130101); H04B 1/38 (20130101) |
Current International
Class: |
H01Q
1/24 (20060101); H04B 1/38 (20060101); H01Q
001/24 (); H01Q 001/38 () |
Field of
Search: |
;343/702,769,846,767,841 |
References Cited
[Referenced By]
U.S. Patent Documents
Foreign Patent Documents
Primary Examiner: Wimer; Michael C.
Attorney, Agent or Firm: Ostrolenk, Faber, Gerb &
Soffen
Claims
What is claimed is:
1. A portable radio communication apparatus, comprising:
an antenna,
an insulating case, and
a printed board having first and second opposed surfaces and a
radio communication circuit including a ground pattern and a
feeding point, said printed board disposed in said insulating case,
and said insulating case having an inner surface opposed to and
separated from one of said first and second opposed surfaces of
said printed board to define a space therebetween,
wherein said antenna is a conductive film coated on first
predetermined region of said inner surface of said insulating
case;
a conductive ground film coated on a second region of the inner
surface of said insulating case, other than said first
predetermined region but coplanar with said first region, said
conductive ground film surrounding said antenna conductive film
such that a C-shaped slot having a constant width is formed and
defined between said antenna conductive film and said conductive
ground film;
a first conductive member connecting said antenna conductive film
with said conductive ground film;
a plurality of second conductive members extending within said
space and connecting said conductive ground film with said ground
pattern of said radio communication circuit; and
a feeding member extending within said space and connecting said
antenna conductive film with said feeding point of said radio
communication circuit.
2. A portable radio communication apparatus as claimed in claim 1,
wherein each of said second conductive members is a conductive rod,
said conductive rod having opposite ends fixedly connected to said
conductive ground film and said ground pattern, respectively.
3. A portable radio communication apparatus as claimed in claim 1,
wherein said feeding member is a conductive rod, said conductive
rod having opposite ends fixedly connected to said antenna
conductive film and said feeding point, respectively.
4. A portable radio communication apparatus as claimed in claim 1,
wherein said first conductive member is a film.
Description
BACKGROUND OF THE INVENTION
The present invention relates to a portable radio communication
apparatus and, in particular, to a structure of a case including an
antenna and an electromagnetic shield in such a portable radio
communication apparatus.
A conventional portable radio communication apparatus comprises a
printed board implemented with a radio communication circuit
including a ground pattern and an antenna terminal pad for
connecting to an antenna member, a shield case covering the printed
board, the antenna member supported on an outer surface of the
shield case and electrically connected to the antenna terminal pad,
and an insulating case housing the shield case and the printed
board.
The shield case has a top surface, a recessed surface, and a
connecting surface between the top surface and the recessed
surface. The antenna member with a predetermined length and width
is fixedly supported on the recessed surface by a conductive
supporting member and is away from the connecting surface. A
feeding member is connected to the antenna member at one end. The
feeding member has an opposite end which serves as a feeding point.
This feeding point is connected to the antenna terminal pad on the
printed board by an inner conductor of a coaxial cable. An outer
conductor of a coaxial cable connects the shield case to the ground
pattern on the printed board.
According to the structure of the conventional apparatus as
described above, since the shield case is inserted into the mold
case, the mold case and the shield case must be designed and
produced with a predetermined clearance therebetween. Thus, it is
difficult to make the apparatus small in size. In addition to this,
the number of parts which form the apparatus increase.
This makes the apparatus large in size and weight and high in
cost.
SUMMARY OF THE INVENTION
It is therefore an object of this invention to provide a portable
radio communication apparatus which is small in size and weight and
low in cost.
On describing the gist of this invention, it is possible to
understand that a portable radio communication apparatus comprises
an antenna, an insulating case having an inner surface, a printed
board having a radio communication circuit including a ground
pattern and an antenna terminal pad.
According to this invention, the above-described portable radio
communication apparatus is characterized by an antenna being a
conductive film coated on a predetermined region of the inner
surface of the insulating case, conductive ground film coated on
the remaining region of the inner surface of the insulating case
with a constant gap from the outer periphery of the antenna
conductive film, first conductive member connecting the antenna
with the conductive ground film, a plurality of second conductive
members connecting the conductive ground film with the ground
pattern, and feeding member connecting the antenna conductive film
with the antenna terminal pad.
BRIEF DESCRIPTION OF THE DRAWING
FIG. 1 is a partial perspective view of a conventional portable
radio communication apparatus;
FIG. 2 is a partial perspective view of a portable radio
communication apparatus according to an embodiment of this
invention; and
FIG. 3 is a partial sectional view taken substantially along the
line 3--3 in FIG. 2.
DESCRIPTION OF THE PREFERRED EMBODIMENT
Referring to FIG. 1, a conventional portable radio communication
apparatus will be described for a better understanding of this
invention. The portable radio communication apparatus comprises a
printed board 11, a shield case 13, an antenna member 15, and an
insulating case 17. The printed board 11 having a radio
communication circuit 19 including a ground pattern 21 and an
antenna terminal pad 23. The shield case 13 contains the printed
board 11 and electromagnetically shields the printed board 11. The
shield case 13 has a top surface 25, a recessed surface 27 and a
connecting surface 29 between the top surface 25 and the recessed
surface 27. The antenna member 15 has a predetermined length and
width and is fixedly supported by a conductive supporting member 31
on the recessed surface 27 of the shield case 13 but away from the
connecting surface 29. A feeding member 33 is connected to the
antenna member 15 at one end and has an opposite end which serves
as a feeding point P. This feeding point P is connected to the
antenna terminal pad 23 on the printed board 11 by an inner
conductor of a coaxial cable 35. An outer conductor of the coaxial
cable 35 connects the shield case 13 to the ground pattern 21 on
the printed board 11. The length of the conductive supporting
member 31 defines a distance between the antenna member 15 and the
recessed surface 27. The feeding member 33 is substantially short
of the length of the conductive supporting member 31.
The above-described portable radio communication apparatus has a
problem as described in the preamble.
Referring to FIGS. 2 and 3, description will proceed to a portable
radio communication apparatus according to an embodiment of this
invention. The illustrated portable radio communication apparatus
comprises a printed board 11, an antenna of a conductive film 37,
and an insulating case 17. The insulating case 17 contains the
printed board 11 and has an inner surface that is opposed to the
printed board 11 with a space provided in-between as shown in FIG
2. The printed board 11 has a radio communication circuit 19
including a ground pattern 21 and an antenna terminal pad 23. The
antenna film 37 has a length L and a width W and is coated on a
predetermined region of the inner surface of the insulating case
17. The resonance frequency is determined by adjusting the length L
and the width W of the antenna film 37. A conductive ground film 39
is coated on the remaining region of the inner surface of the
insulating case 17 with a constant gap 41 from the outer periphery
of the antenna film 37. In detail, the antenna film 37 is
surrounded by the conductive ground film 39 with the constant gap
41. A first conductive member 43 is a conductive film formed at a
part of the constant gap 41 and connects electrically and bridges
the antenna film 37 with the conductive ground film 39. The width
of the first conductive film 43 is smaller than the width of the
antenna member 15. Each of the antenna film 37, the conductive
ground film 39, and the first conductive film 43 is formed by
evaporating or painting the conductive material, such as copper or
aluminium, on the inner surface of the insulating case 17. A
plurality of second conductive members 45 are connected with the
conductive ground film 39. The second conductive members 45 are
conductive rods each having opposite ends fixedly connected to the
conductive ground film 39 and the ground pattern 21, respectively.
A feeding member 33 is a conductive rod and has opposite ends
fixedly connected to the antenna film 37 and the antenna terminal
pad 23, respectively. A desired standing wave ratio is determined
by adjusting the distance between the first conductive member 43
and the feeding member 33. The connecting position at which the
antenna film 37 and the feeding member 33 are connected is
determined by the distance.
As apparent from FIG. 3, because the first conductive ground film
39 which is coated on the insulating case 17 functions as an
electromagnetic shield, the shield case 13 illustrated in FIG. 1 is
useless. Thus, no clearance is necessary between the first
conductive ground film 39 and the insulating case 17, so that the
portable radio communication apparatus is produced with a small
size and a reduced cost.
* * * * *